Three dimensional technology has been developing for over a century, yet has never been able to establish itself in the mainstream generally due to complexity and cost for the average user. The emergence of Liquid Crystal Display (LCD) and Plasma screens which are better suited to rendering three dimensional (3D) images than traditional Cathode Ray Tube (CRT) monitors and televisions in both consumer electronics and the computer world has spurred interest in the technology. 3D systems have progressed from being technical curiosities and are now becoming practical acquisition and display systems for entertainment, commercial and scientific applications. With the boost in interest, many hardware and software companies are collaborating on 3D products.
Recently, NTT DoCoMo unveiled the Sharp mova SH251iS handset which is the first to feature a color screen capable of rendering 3D images. A single digital camera allows its user to take two dimensional (2D) images and, then using an editing system, convert them into 3D. The 3D images are sent to other phones with the recipient able to see the 3D images if they own a similarly equipped handset. No special glasses are required to view the 3D images on the auto-stereoscopic system. There are a number of problems with this technology though. In order to see quality 3D images, the user has to be positioned directly in front of the phone and approximately one foot away from its screen. If the user then moves slightly he will lose focus of the image. Furthermore, since only one camera is utilized, it can only take a 2D image and then via the 3D editor, the image is artificially turned into a 3D image. Quality of the image is therefore an issue.
One method of producing a stereoscopic image from a 2D image has been patented in U.S. Pat. No. 6,477,267 to Richards whereby at least one object is identified in the original image; the object or objects are outlined; a depth characteristic is defined for each object; and selected areas of the image are displaced accordingly. As discussed above though, converting a 2D image into a 3D image has a number of problems, most importantly, the quality of the resulting 3D image.
Instead of capturing a 2D image with one camera, U.S. Pat. No. 6,664,531 to Gartner et al., discloses a possible configuration to capture a pair of images using two cameras, which observe the parallax effect of an object. Then the left eye will view one image of this pair of stereoscopic images and the right eye will view the other. The human brain is able to easily merge this pair of images so that the object is viewed as a 3D image.
Another example of acquiring a 3D image with two cameras is disclosed in U.S. Pat. No. 6,512,892 to Montgomery et al. which includes a 3D camera with at least two moveable parallel detector heads.
As described for the DoCoMo product, a user must stay essentially still while viewing a 3D image otherwise he will lose focus. One reason for such an issue is that the image is a multi-image display. Multi-image displays include different images interleaved into a single display medium. The simplest implementation of multi-image displays includes repeating a sequence of left-right images. The distance between each successive image is 65 mm which is equal to the average distance between the viewer's eyes. However, if the viewer moves left or right more than 32 mm, then the viewer will see a reverse 3D image. The reverse 3D image is uncomfortable to view and will cause headaches and pain after a while.
The multi-image display can be improved by utilizing a number of images, each spaced apart by 65 mm. With a number of images, the viewer can move his head left or right and will still see a correct image. However, there are additional problems with this technique. The number of cameras required increases. For example, to have four views, four cameras are needed. Also, since the sets of numbers are repeating, there will still be a position that results in a reverse 3D image, just fewer of them. The reverse image can be overcome by inserting a null or black field between the repeating sets. The black field will remove the reverse 3D issue, but then there are positions where the image is no longer 3D. Furthermore, the number of black fields required is inversely proportional to the number of cameras utilized such that the more cameras used, the fewer black fields required. Hence, the multi-image display has a number of issues that need to be overcome for the viewer to enjoy his 3D experience.
There are a wide variety of viewing apparatuses presently available for viewing 3D images. One type includes viewing apparatuses which require lenses, prisms, or mirrors held in proximity with the viewer's eyes, which are generally less convenient than alternatives which do not require special eyewear. A second type includes lenticular systems which are relatively difficult and expensive to manufacture for high quality image presentation due to the amount of precision associated with their production, if high-resolution images are desired. Moreover lenticular systems will always present images having a lower resolution than the resolution of which the display device to which the lenticular array is attached to is inherently capable. Furthermore, lenticular systems are not well adapted for viewing systems such as computer displays and television, and are therefore not in wide use.
A third type of 3D image viewing apparatus includes parallax barriers for 3D viewing. The systems are grids consisting of transparent sections interspersed with opaque sections that are placed in various relationships to the image being seen or projected, the image is an interspersed composition of regions taken from the left image (to be eventually seen only by the left eye of the viewer) and regions taken from the right image (to be eventually seen only by the right eye of the viewer), the grid or grids being placed in positions which hide regions of the right image from the left eye and hide regions of the left image from the right eye, while allowing each eye to see sections of the display which are showing regions originating from its appropriate image. In such a system, roughly half of the display contains no image.
A fourth type of 3D image viewing apparatus disclosed in U.S. Pat. No. 6,252,707 to Keinberger et al., includes a system for viewing and projection of full-color flat-screen binocular stereoscopic viewing without the use of eyeglasses. Various combinations of light polarizing layers and layers of light rotating means or color filters are used to display a left and right image to the appropriate left or right eye.
One possible option for solving the problems described regarding the multi-image display is a tracking system. U.S. Pat. No. 6,163,336 to Richards discloses an auto-stereoscopic display system with a tracking system. Richards teaches a tracking system that is aware of the position of the viewer and can instruct the display unit to move the position of the displayed images so that they correspond to the correct position of the viewer.
Another problem is the Passive Auto Focus system used in modern digital cameras which function based on measuring the high frequency content of the picture and changing the focus setting until this measure reaches the maximum. Such a method is slow and fails frequently. U.S. Pat. No. 6,616,347 to Dougherty discloses a number of dual camera systems for autofocusing as prior art, although they all have problems including being too bulky, costly, and heavy. Furthermore, there were difficulties aligning parts of the images from the two cameras. U.S. Pat. No. 6,611,268 to Szeliski et al. discloses utilizing two video cameras where at least one of the cameras is a video camera to estimate the depth map of a scene.
Furthermore, while a number of wireless hand-held digital cameras exist as disclosed in U.S. Pat. No. 6,535,243 to Tullis, such wireless devices are devoid of 3D capabilities. Hence the need to explore such possibilities further.
Projection of 3D images has also been developed in the past, but there is a need for advancement. U.S. Pat. No. 6,252,707 to Kleinberger et al. discloses a 3D projector system that comprises of two projectors which project a 3D image on a screen without the need for special eyewear. The projectors have been a motion picture projector, a television projector, a computer-driven projection device, a slide projector, or some other equipment similar in size, hence the size of these projectors is quite large.
Additional technologies have also been developed. Disney created what is called Disney Digital 3D which presents a CGI movie in 3D using special technology that requires only one digital projector.
Philips has developed an auto-stereoscopic lenticular LCD monitor that displays both 2D and 3D images where people at different angles are able to view the screen without special viewing glasses. Philips has also developed a signal processing processor for mobile phones that enables 3D to be rendered in real time.